Regression with imputed covariates: a generalized missing indicator approach

International audienceA common problem in applied regression analysis is that covariate values may be missing for some observations but imputed values may be available. This situation generates a trade-off between bias and precision: the complete cases are often disarmingly few, but replacing the missing observations with the imputed values to gain precision may lead to bias. In this paper we formalize this trade-off by showing that one can augment the regression model with a set of auxiliary variables so as to obtain, under weak assumptions about the imputations, the same unbiased estimator of the parameters of interest as complete-case analysis. Given this augmented model, the bias-precision trade-off may then be tackled by either model reduction procedures or model averaging methods. We illustrate our approach by considering the problem of estimating the relation between income and the body mass index (BMI) using survey data affected by item non-response, where the missing values on the main covariates are filled in by imputations

Endoscopic palliative management of esophageal and tracheal rupture

The increasing number of patients requiring intensive care and airway support has led to a growing recognition that significant short- and long-term morbidity may be associated with the use of artificial airways; this is despite significant improvements in the materials used in laryngeal tubes, which aim to decrease the trauma associated with long-term intubation. We present the first case, to our knowledge,of huge, nontraumatic, esophageal perforation, widely communicating with the trachea, and which was treated successfully with double endoscopic stent placement

Surgical treatment of solitary sternal metastasis from breast cancer Case report

Bone metastasis is a frequent and early complication of breast cancer. This case report describes a technique for a partial exeresis of the sternum and the reconstruction of the pleura with autologous dermis from the lower abdomen and the loss of substance with a myocutaneous flap

Frontal brain asymmetries as effective parameters to assess the quality of audiovisual stimuli perception in adult and young cochlear implant users

How is music perceived by cochlear implant (CI) users? This question arises as "the next step" given the impressive performance obtained by these patients in language perception. Furthermore, how can music perception be evaluated beyond self-report rating, in order to obtain measurable data? To address this question, estimation of the frontal electroencephalographic (EEG) alpha activity imbalance, acquired through a 19-channel EEG cap, appears to be a suitable instrument to measure the approach/withdrawal (AW index) reaction to external stimuli. Specifically, a greater value of AW indicates an increased propensity to stimulus approach, and vice versa a lower one a tendency to withdraw from the stimulus. Additionally, due to prelingually and postlingually deafened pathology acquisition, children and adults, respectively, would probably differ in music perception. The aim of the present study was to investigate children and adult CI users, in unilateral (UCI) and bilateral (BCI) implantation conditions, during three experimental situations of music exposure (normal, distorted and mute). Additionally, a study of functional connectivity patterns within cerebral networks was performed to investigate functioning patterns in different experimental populations. As a general result, congruency among patterns between BCI patients and control (CTRL) subjects was seen, characterised by lowest values for the distorted condition (vs. normal and mute conditions) in the AW index and in the connectivity analysis. Additionally, the normal and distorted conditions were significantly different in CI and CTRL adults, and in CTRL children, but not in CI children. These results suggest a higher capacity of discrimination and approach motivation towards normal music in CTRL and BCI subjects, but not for UCI patients. Therefore, for perception of music CTRL and BCI participants appear more similar than UCI subjects, as estimated by measurable and not self-reported parameters

Tightness for a stochastic Allen--Cahn equation

We study an Allen-Cahn equation perturbed by a multiplicative stochastic noise which is white in time and correlated in space. Formally this equation approximates a stochastically forced mean curvature flow. We derive uniform energy bounds and prove tightness of of solutions in the sharp interface limit, and show convergence to phase-indicator functions.Comment: 27 pages, final Version to appear in "Stochastic Partial Differential Equations: Analysis and Computations". In Version 4, Proposition 6.3 is new. It replaces and simplifies the old propositions 6.4-6.

No phenotypic differences for polycystic ovary syndrome (PCOS) between women with and without type 1 diabetes mellitus.

CONTEXT: Women with type 1 diabetes mellitus (DM1) have a higher prevalence of polycystic ovary syndrome (PCOS) than the general population. OBJECTIVE: The aim of this study was to clarify, in DM1 women with PCOS (PCOS-DM1), the influence of insulin therapy and glycemic control and evaluate the hormonal and phenotypic differences with age-matched and body mass index (BMI)-matched women with PCOS without diabetes. DESIGN, SETTING, AND PATIENTS: We evaluated 103 DM1 women with and without PCOS treated with intensive insulin therapy; 38 age-matched and BMI-matched women with PCOS without diabetes were compared in a cross-sectional study. OUTCOME MEASUREMENTS: Clinical, anthropometric, and metabolic parameters were evaluated. Hormonal evaluation and ovary ultrasound were performed during the follicular phase of the menstrual cycle. RESULTS: Applying the diagnostic criteria of the Androgen Excess Society, 38 (36.89%) women with DM1 showed PCOS. The 38 PCOS-DM1 women showed no differences in treatment and glycemic control compared with DM1 women without PCOS. The only difference was a higher visceral adiposity index in PCOS-DM1 (1.21±0.70 vs 0.90±0.32; P=.002). PCOS-DM1 showed no phenotypic differences with age-matched and BMI-matched PCOS without diabetes. The hormonal pattern was similar except that higher levels of Δ4androstenedione were found in PCOS-DM1 (12.89±3.49 vs 2.79±1.75 nmol/L; P=.010). CONCLUSIONS: The women with PCOS-DM1 do not exhibit particular phenotypic characteristics compared with nondiabetic women with PCOS. However, this pathological disorder must not be underestimated because it could be an additional cardiovascular risk factor in women with DM1

Trocar-related abdominal wall bleeding in 200 patients after laparoscopic cholecistectomy: Personal experience

AIM: To determine the complications and incidence of the first and second access-related vascular injuries induced by videolaparoscopic cholecistectomy. METHODS: We retrospectively reviewed vascular injuries in 200 consecutive patients who underwent videolaparoscopic cholecistectomy from 2003 to 2005. One hundred and one patients with placement of radial expanding trocars were assigned into group A and 99 patients with placement of pyramidal tipped trocars into group B. All the patients were submitted to open access according to Hasson for the first trocar. RESULTS: Bleeding did not occur at the intraoperative cannula-site in group A. However, it occurred at the intraoperative cannula-site of 7 patients (7.1%) in group B, with a statistically significant difference (P < 0.01). No mortality was registered. More vascular lesions were found in group B. CONCLUSION: The advantage of Hasson technique is that peritoneal cavity access is gained under direct vision, preventing most severe injuries. The open technique with radial expanding trocars is recommended for secure access to the abdominal cavity in videolaparoscopy. Great care should be taken to avoid major complications and understanding the abdominal wall anatomy is important for reducing bleeding during or after s placement of trocars

Bipolar Quantum Molecular Resonance versus Blunt Dissection tonsillectomy

Bipolar Quantum Molecular Resonance versus Blunt Dissection tonsillectomy. Objectives: This study compared a quantum molecular resonance tonsillectomy (QMRT) to a standard blunt dissection tonsillectomy (BDT) for effectiveness and safety. Methodology: From January 2011 to September 2012, we recruited 80 children (ages 3 to 16 y) with paediatric obstructive sleep apnoea syndrome and/or recurrent tonsillitis. Patients were randomly assigned to receive QMRT (N = 40) or BDT (N = 40). The operating time and blood loss during surgery were evaluated. During the first postoperative week, the patients' parents completed a questionnaire to evaluate bleeding, ear and neck pain, nausea, vomiting, interrupted sleep, oral liquid intake or discomfort in fluid assumption, and analgesic consumption. Results: The average tonsillectomy duration was significantly shorter in the QMRT group (22.07 min \ub1 9.05) than in the BDT group (35.12 min \ub1 13.32; p < 0.000005). The average blood loss during tonsillectomy was significantly lower for the QMRT group (5.62 ml \ub1 7.44) than for the BDT group (43 ml \ub1 33.20; p < 000000001). However, the BDT group reported significantly lower pain scores than the QMRT group on days 2 (p < 0.05), 5 (p < 0.05), and 6 (p < 0.05); on other days, the groups were not significantly different. The BDT group reported two early and one late bleeding episodes; the QMRT group recorded only two late bleeding episodes. Conclusions: QMRT significantly reduced the operating time and intra-operative blood loss. No significant differences were found between the two techniques in postoperative pain or bleeding

The effect of body mass index on chest trauma severity and prognosis

AIM: Patients with thoracic trauma constitute one third of all the trauma cases, in west Sicily were recorded 941 thoracic trauma during the period between 2006 and 2009. Sicily is one of the Italian regions with the highest rate of obesity: some studies have demonstrated that obesity is an independent risk factor for mortality in high energy blunt traumas. MATERIAL OF STUDY: This study was conducted with trauma patients older than 20 years old who presented to our Department during the last five years. We only included thoracic injuries and politrauma with a thoracic involvement and a BMI > 25- Patients were divided into two groups: HET and LET patients. RESULTS: Thoracic trauma was more common in patients with a BMI > 25 than in normo-weight and clinic admission rate, length of hospital stay and ISS score increased in proportion with the increase of BMI. Both HET (high energy trauma) and LET (low energy trauma) revealed that overweight, obese and morbidly obese patients had greater admissions and length of hospital stay. DISCUSSION: The overweight and obese population has increased substantially over the last two decades and 61,5% of the Sicilian population is above normal weight. A large body mass with excess adiposity may contribute to HET injuries in several ways. Obesity has a number of comorbidities that reduce chances of recovery in overweight and obese patients experienced thoracic trauma both HET and LET. CONCLUSION: Obesity increases morbidity independently of injury severity in thoracic trauma patients. As BMI increased, length of hospital stay increased and prognosis deteriorates

Therapeutic sequences in patients with grade 1−2 neuroendocrine tumors (NET): an observational multicenter study from the ELIOS group

Purpose: Many different treatments are suggested by guidelines to treat grade 1−2 (G1−G2) neuroendocrine tumors (NET). However, a precise therapeutic algorithm has not yet been established. This study aims at identifying and comparing the main therapeutic sequences in G1−G2 NET. Methods: A retrospective observational Italian multicenter study was designed to collect data on therapeutic sequences in NET. Median progression-free survival (PFS) was compared between therapeutic sequences, as well as the number and grade of side effects and the rate of dose reduction/treatment discontinuation. Results: Among 1182 patients with neuroendocrine neoplasia included in the ELIOS database, 131 G1–G2 gastroenteropancreatic, lung and unknown primary NET, unresectable or persistent/relapsing after surgery, treated with ≥2 systemic treatments, were included. Four main therapeutic sequences were identified in 99 patients: (A) somatostatin analogs (SSA) standard dose to SSA high dose (n = 36), (B) SSA to everolimus (n = 31), (C) SSA to chemotherapy (n = 17), (D) SSA to peptide receptor radionuclide therapy (PRRT) (n = 15). Median PFS of the second-line treatment was not reached in sequence A, 33 months in sequence B, 20 months in sequence C, 30 months in sequence D (p = 0.16). Both total number and severity of side effects were significantly higher in sequences B and C than A and D (p = 0.04), as well as the rate of dose reduction/discontinuation (p = 0.03). Conclusions: SSA followed by SSA high dose, everolimus, chemotherapy or PRRT represent the main therapeutic sequences in G1−G2 NET. Median PFS was not significantly different between sequences. However, the sequences with SSA high dose or PRRT seem to be better tolerated than sequences with everolimus or chemotherapy